Steviol glycosides are sweet-tasting compounds extracted from the stevia plant (Stevia rebaudiana Bertoni). Typically, these compounds are found to include stevioside, steviolbioside, the Rebaudiosides, including Rebaudioside A (Reb A), Rebaudioside B (Reb B), Rebaudioside C (Reb C), Rebaudioside D (Reb D), and Rebaudioside E (Reb E), and dulcoside A. Many steviol glycosides are potent, non-nutritive sweeteners. Steviol glycosides comprise a diterpene core (formula I) substituted at R1 and R2 with various combinations of hydrogen, glucose, rhamnose, and xylose.
For example, R1 may be hydrogen, 1-β-D-glucopyranosyl, or 2-(1-β-glucopyranosyl)-1-β-D-glucopyranosyl, and R2 may be hydrogen, 1-β-D-glucopyranosyl, 2-(1-β-D-glucopyranosyl)-1-β-D-glucopyranosyl, 2,3-bis(1-β-D-glucopyranosyl)-1-β-D-glucopyranosyl, 2-(1-α-L-rhamnopyranosyl)-1-β-D-glucopyranosyl, 2-(1-α-L-rhamnopyranosyl)-3-(1-β-D-glucopyranosyl)-1-β-D-glucopyranosyl, or 2-(1-β-D-xylopyranosyl)-3-(1-β-D-glucopyranosyl)-1-β-D-glucopyranosyl. Rebaudioside A (wherein R1 is 1-β-D-glucopyranosyl and R2 is 2,3-bis(1-β-D-glucopyranosyl)-1-β-D-glucopyranosyl) has a sweetness of about 200 to 300 times the sweetness of sucrose.
Steviol glycosides are found in the leaves of the stevia plant and each have a particular taste profile and sweetness intensity. Since receiving GRAS status, Reb A has become a popular naturally occurring potent sweetener in the food and beverage industry. Reb A is approximately 200 times sweeter than sucrose, but the sweetness may be offset by problems of off-tastes, for example slow on-set, or bitter, licorice, or lingering aftertaste. Reb D is one of the other sweet steviol glycosides and has a sweetness intensity similar to Reb A, but possesses a more desirable taste profile than many of the other steviol glycosides, including Reb A, Stevioside, Reb C, Reb E, and dulcoside A. Unfortunately, the water solubility of commercially available Reb D is low. This leads to difficulties in making certain Reb D sweetened products, e.g., carbonated beverages, using traditional bottling process methods.
Traditionally, the beverage industry makes certain carbonated beverages by first making concentrated syrup and then diluting the syrup with water at the time and place of making the beverage. The dilution ratio in such beverages is often 1:5, meaning one part syrup is mixed with five parts water. The beverage often is carbonated at the time of being bottled or otherwise packaged. For any ingredient to be incorporated into such a 1:5 syrup, the solubility of the ingredient in the syrup must be at least six times higher than its desired concentration in the finished beverage. Therefore, when comparing the solubility of compounds such as Stevioside (which is found to be only sparingly soluble in water) to Reb A (which contains an additional glucose unit on its structure), Reb A is found to be more soluble than Stevioside. The solubility of Reb A in aqueous solution at room temperature is at least 3000 ppm, enabling the production of a beverage (e.g., carbonated beverage, juice beverage, energy drink, and the like) with a concentration of about 500 ppm of Reb A. In contrast, the stable solubility of Reb D in aqueous solution at room temperature has been found to be no more than about 450 ppm, yielding a beverage containing only about 74 ppm of Reb D. For many beverages, this concentration does not yield a sufficiently effective level of sweet taste to the beverage.
Conventional methods for increasing the solubility of a solid solute in solution include increasing the temperature of the solution. Upon heating Reb D in aqueous solution at temperatures ranging from about 70°-80° C., the solubility of Reb D increases to as much as 0.6%, (6000 ppm), with no apparent decomposition. However, upon cooling the solution to room temperature (e.g., 25° C.), the Reb D precipitates back out of solution within a few hours. The formation of precipitate disrupts and disables the processes utilized in traditional beverage manufacturing.
It is an object of the present disclosure to provide a new, more soluble thermally stable form of Reb D as well as syrups, solutions, beverages, sweeteners, compositions and other products comprising the new soluble thermally stable form of Reb D either alone or with other ingredients. Additional objects, features and advantages will be apparent from the following disclosure and from the discussion of various exemplary embodiments.